392 On the Fossil Fishes of the Carboniferous Limestone Series of Great, Britain. 
crown of the tooth is sub-triangular, the ridge being quite as far removed from the 
base as the tooth is broad, whilst in the Bristol specimens, the teeth are broad and 
much depressed. The teeth of O. ramosus from Oreton are beautifully preserved, 
the surface decoration being particularly distinct and clear. The primary divaricat- 
ing ridges are much fewer than in either the Bristol or Armagh forms, they are 
irregularly branched, and, especially on the median cone, are somewhat complex. 
The crown is slightly raised in the centre, due simply to the greater thickness of 
the median cone, the base of the crown is approximately straight, and from the 
summit of the median cone the lateral extensions gradually thin out, at the same 
time the antero-posterior diameter becomes contracted and the termination is, 
compared with the others, very acute. 
The great fishes of this species which occupied the area around Bristol appear to 
have had congeners in other localities, of smaller size and, so far as the teeth are 
concerned, somewhat modified form; they do not present, however, sufficiently diver- 
gent characteristics to warrant the supposition that they were not the same species. 
Formation and locality : Mountain Limestone, Bristol ; Oreton ; Armagh. 
Ex voll. Earl of Enniskillen ; Bristol Museum ; Museum of the Geological Society, London. 
Orodus cinctus, Agass. 
(2b Ie, ites, B Y,) 
Orodus cinctus—L. Agassiz, 1838. ‘Rech. s. les Poiss. Foss.,” Vol. IIT., p. 96, pl. xi, figs. 1-4. 
. s J. E. Portlock, 1843. “Geol. Report, Londonderry, &c.,” p. 467. 
+ : C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. I., pt. 3, p. 342. 
is * H. G. Bronn, 1848. ‘ Nomencl. Paleont.,” p. 852. 
5 . F. J. Pictet, 1854. *‘Traité de Paléont,” Vol. II., p. 264. 
5 5 J. Morris, 1854. ‘Catal. of Brit. Foss.,” p. 335. 
3 5 Morris & Roberts, 1862. ‘ Quart. Journ. Geol. Soc.,” Vol. XVIII., p. 101. 
% Young& Armstrong, 1871. “ Trans. Geol. Soc. of Glasgow,” Vol. III., supt., p. 73. 
99 L. G. de Koninck, 1878. “ Fauna du Cale. Carbonif. de la Belgique,” p. 31, pl. iv., 
fig. 2, 4 
- . J.J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 359. 
Teeth, medium size, rounded and smooth, transverse diameter equal to four times 
or more that of the antero-posterior one. Median surface of crown largely 
developed, forming a rotund, smooth, somewhat detached cone, with a more or less 
deep sulcus extending across the tooth antero-posteriorly. Lateral prolongations 
of the coronal surface taper gradually towards each extremity which is usually 
obtusely rounded. There is no central carina as in O. ramosus. Three or four 
rather deep sulci extend across the tooth from front to back, on each side of the 
median cone, surface uniformly punctate. Root, large, laterally co-extensive with 
the crown, about double the depth of the central cone ; structure, porous, vesicular. 
Length of tooth 1:4 inches in lateral diameter, antero-postero diameter °35 inch, 
thickness including base °6 of an inch. 
This tooth is distinguished from that of Orodus ramosus by the absence of the 
lateral median carina and in the general simplicity of its coronal surface. 
